Hello,
I have problem with playback of MKV files with non-square pixels. I did a simple test - I put a 4:3 AVI into MKV and set the AR to 16:9 (in MKVToolnix 1.5). If I try to play the file, it always plays as 4:3.
I tried MPC with internal a Haali's splitter and ViPlay with Haali's splitter. I used FFDShow and DivX for decoding the video stream.
Why doesen't this work? Is it because of a splitter or decoder mistake? Or did I make a mistake in creating the file?

I tried to enable it, but it didn't help (FFDShow 21/12/05). It works in VLC.
In fact how should it work in DirectShow? I think the splitter should read the information about aspect ratio and should forward it to video decoder, right? Can I somehow check if FFDShow got this information or not? Or does FFDShow prefer information stored in MPEG-4 video stream? It shouldn't IMHO.

You need to set overlay mixer in ffdshow to third state for this to work.

What do you mean by "third state" of overlay?

Anyway I found out I have checked in MPC "Keep Aspect Ratio" and this was causing the problem. Now it finally works in MPC, but it still doesen't work in ViPlay. I believe it will be the same case with most other DS players. If FFDShow is only signalling the AR to a player, the player has to support it. So this will be probably the reason why it will only work in a few players. Wouldn't it be better if FFDShow would resize the movie to the correct AR?

I did some more tests with AR. I found out, that if I disable "Keep Aspect Ratio" then I don't have right AR for DVDs. So I either have correct AR for MKV or DVD, but not both.
I also wanted to do some tests with AR in m4v stream. I modified a test file with MPEG4 Modifier, but it seems to me the program is not working correctly. GSpot still says that PAR is 1:1 and if I try to load the file in MPEG4 Modifier, the AR is different to what I have set.

So my conclusion from these experiences is not to use non-square pixels if possible. It is still not working flawlesly.

I also wanted to do some tests with AR in m4v stream. I modified a test file with MPEG4 Modifier, but it seems to me the program is not working correctly. GSpot still says that PAR is 1:1 and if I try to load the file in MPEG4 Modifier, the AR is different to what I have set.

MPEG4 Modifier only supports MPEG-4 ASP in an AVI container. Was your file like this? Also, DAR cannot be directly written to the file, it is converted to PAR first based on the resolution of the video, so this may be why you see a different value after re-loading the file.

Thank you Moitah,
I did a mistake in reading the information in your porgram. One file was an AVI compressed using DivX 5, I thought the displayed value is DAR, but it was PAR. So the file was modified correctly. The other file was an AVI/DivX 3. So it probably won't work because it is MPEG-4 SP.
Unfortunately the problem with playback remains. FFDShow and DivX ignore the PAR, only XviD decoder works. But again only in MPC with checked "Keep Aspect Ratio". It also works in VLC.
This is strange, because I thought FFDShow supports reading PAR. But it probably doesen't :-(